If Operation SUNRISE represents the role that OSS played to bring about the conclusion of the war by strategic means (the high level discussions between senior German and Allied officials). then the use of low level agents to counter enemy intelligence activities took more of a tactical character. The responsibility fell to OSS's X-2, or counterespionage branch. X-2 collected information on Axis intelligence organizations and espionage activities while protecting OSS from penetration. Following its establishment in 1943, X-2 also maintained security of OSS's own operations, "vetted" or conducted background checks on OSS employees and agents, and acted in a liaison capacity with other American counterintelligence agencies and with foreign intelligence services.